The present invention relates to a disc drive microactuator system and more particularly to an improved structure and fabrication method for precise placement of components in an electromagnetic microactuator.
The density of concentric data tracks on magnetic discs continues to increase (that is, the width of data tracks and radial spacing between data tracks are decreasing), requiring more precise radial positioning of the head. Conventionally, head positioning is accomplished by operating an actuator arm with a large-scale actuation motor, such as a voice coil motor, to radially position a slider (which carries the head) on a flexure at the end of the actuator arm. The large-scale motor lacks sufficient resolution to effectively accommodate high track-density discs. Thus, a high resolution head positioning mechanism, or microactuator, is necessary to accommodate the more densely spaced tracks.
One particular design for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional lower resolution actuator motor, thereby effecting head positioning through dual stage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning. In particular, magnetic microactuator designs featuring a magnet/keeper assembly and coil have been developed. Magnetic microactuators typically include a stator portion and a rotor portion, the stator being attached to the flexure and the rotor supporting the slider. The rotor is movable with respect to the stator such that the slider can be positioned more precisely over a track of a disc.
One challenge of current microactuator design is the positioning and placement of the slider when bonding it into the rotor. Presently, magnetic microactuators have very small tolerances in the relative location and separation distance between components. Current designs of magnetic microactuators have rotors with apertures for the placement of sliders into the microactuator. Apertures are also used for the placement of magnets into the microactuator. Use of apertures does not allow precise control of the separation distance between the magnet and the drive/sense coils, meaning that labor-intensive procedures must be employed during assembly to achieve the proper component spacing and positioning. Increasing the ease of positioning a slider or magnet into the microactuator by use of a positioning reference would decrease the costs of assembly. In particular, positioning references would provide a convenient and local method of properly placing and positioning a slider or magnet into the microactuator.
The present invention is a microactuator for a disc drive. The microactuator finely positions a transducing head above a track on the disc. The transducing head is carried by a slider attached to the frame of the microactuator.
An exemplary embodiment of the microactuator utilizes a bonding tub to secure the slider to the microactuator frame. The bonding tub is formed with a tub cover. The top surface of the slider is engaged to a planar bonding surface on the bottom of the tub cover.
Another embodiment has a bonding tub to engage magnets used for a magnetic microactuator. The bonding tub for the magnets extends upwardly from the bottom of the microactuator frame and has a tub cover at the closed top end of the tub. The top surface of the magnets are engaged to a bonding surface on the bottom of the tub cover and the bottom surface of the magnets are secured to a bottom keeper.